Technical Field
The present inventions relate to a power transmitting apparatus for transmitting or cutting-off the rotational driving power of an engine inputted to an input member to or from an output member.
Description of the Related Art
In general, a power transmission apparatus used in a motorcycle is intended to arbitrarily perform transmission or cutting-off of the driving power of the engine to or from a transmission and a driving wheel and comprises an input member connected to an engine-side, an output member connected to the transmission and driving wheel-side, and a clutch member connected to the output member. The power can be transmitted by press-contacting a plurality of driving-side clutch discs and driven-side clutch discs with each other and can be cut off by releasing the press-contacting force acting on the driving-side clutch discs and driven-side clutch discs.
More particularly, power transmitting apparatuses may comprise a clutch housing rotatable together with an input member and a plurality of driving-side clutch discs mounted thereon, a plurality of driven-side clutch discs arranged between the driving-side clutch discs of the clutch housing alternately therewith, a clutch member connected to an output member, and a pressure member mounted on the clutch member axially movably relative to the clutch member for forcing the driving-side clutch discs and the driven-side clutch discs to be press-contacted with each other and to release the press-contacting force acting on them in accordance with axial movement relative to the clutch member. Such power transmitting apparatuses are constructed to be able to transmit or cut off the driving power of the engine inputted to the input member to or from the output member by press-contacting the driving-side clutch discs with the driven-side clutch discs or by releasing a press-contacting force acting on them.
As disclosed in JP 2005-325993 A, a power transmitting apparatus has been proposed which is provided with a press-contact assisting cam of normal-driving side for increasing the press-contacting force acting on the driving-side clutch discs and the driven-side clutch discs when the rotational driving power of the engine inputted to the input member is transmitted to the output member. According to the power transmitting apparatus of the JP 2005-325993 patent document, since it is possible to increase the press-contacting force between the driving-side clutch discs and the driven-side clutch discs by the press-contact assisting cam of normal-driving side, it is possible to maintain a desirable power transmitting performance, although the power transmitting capacity is reduced by reducing the number of the driving-side and driven-side clutch discs or spring load and thus the size of the power transmitting apparatus is reduced.